Varenicline in the management of smoking cessation: a single technology appraisal

This paper presents a summary of the submission's evidence for the clinical effectiveness and cost-effectiveness of varenicline for smoking cessation included four studies of varenicline (one of which was commercial-in-confidence) and a meta-analysis of varenicline versus nicotine replacement therapy (NRT), bupropion and placebo. Two controlled trials of 12 weeks of varenicline versus sustained-release bupropion and placebo suggested that varenicline results in a statistically significant improvement in the odds of quitting at 12 weeks [odds ratio (OR) for quit rate during last 4 weeks of the study: 1.90-1.93 (p < 0.001) varenicline versus bupropion; 3.85 (p < 0.001) varenicline versus placebo). The ORs for sustained abstinence (weeks 9-52) for varenicline versus bupropion were 1.77 (p = 0.004) and 1.46 (p = 0.057), and for varenicline versus placebo were 2.66-3.09 (p < 0.01). A placebo-controlled maintenance trial examined whether a further 12 weeks of varenicline would maintain the rate of abstinence among those successfully treated on one 12-week course [OR = 2.48 at week 24 for varenicline versus placebo (p < 0.001)]. The meta-analysis suggested that varenicline was superior to placebo and bupropion at 1 year and 3 months. Based on indirect comparisons, varenicline was reported to be superior to NRT when compared with placebo or all controls at 1 year and 3 months. The submission presented a state transition model to estimate the incremental cost-effectiveness of varenicline compared with bupropion, NRT and placebo. The model suggests that varenicline dominates bupropion, NRT and placebo.Treatment efficacy was based on a pooled analysis of 1-year quit rates from the varenicline clinical trials. Assuming a willingness-to-pay threshold range of 20,000-30,000 pounds per quality-adjusted life-year gained, the probabilistic sensitivity analysis suggests that the probability that varenicline produces the greatest amount of net benefit is 0.70. Weaknesses of the manufacturer's submission include the assumption that only a single quit attempt using a single smoking cessation intervention is made, the presence of multiple computational errors and a limited sensitivity analysis. In conclusion, varenicline is likely to be clinically and cost-effective for smoking cessation assuming that each user makes a single quit attempt. The key area of uncertainty concerns the long-term experience of subjects who have remained abstinent from smoking beyond 12 months. The guidance issued by the National Institute for Health and Clinical Excellence in July 2007 states that varenicline is recommended within its licensed indications as an option for smokers who have expressed a desire to quit smoking and that varenicline should normally be prescribed only as part of a programme of behavioral support.